Appeal No. 1997-2319
Application No. 08/147,707
as well as the T-lineage associated antigens CD5 and CD7. Terstappen, Abstract,
Introduction and page 1225.
McClanahan describes PCR experiments assessing the levels of mRNA
corresponding to various growth factor receptor subunits and protooncogenes in
developing mouse hematopoietic cells. “Of the genes whose expression changed
during in vitro differentiation, the IL-7R gene displayed the most dramatic increase at
later states of development,” thus, McClanahan suggests that “this may be evidence of
lymphoid lineage commitment,” although it is not known whether “all of the receptor
mRNAs expressed in [embryonic stem] cells lead to the production of functional
proteins, or if these molecules are expressed on the surface.” Pages 2912-13.
Armitage describes monoclonal antibodies specific for IL-7 receptors.
According to the examiner (Examiner’s Answer, pages 7 and 8, brackets in the
original),
It would have been obvious to one of ordinary skill in the art . . . to perform
three-color FACS protocols to isolate populations of human cells,
employing CD34-, and CD38-specific mAbs, according to the method of
Terstappen, and including as the third antibody one of the IL-7R-specific
mAbs disclosed by Armitage in place of any of the third antibodies
employed by Terstappen, because Terstappen teaches that CD34+ CD38+
cells are lineage committed, and because McClanahan teaches that the
expression of mRNA for the [high affinity] IL-7R, which the artisan would
reasonably have expected to correlate with the expression of the IL-7R
protein on the surface of the cell, is likely to be characteristic of lymphoid
commitment. The artisan accordingly would have expected that FACS
selection for the expression of all three of these markers . . . would yield a
population of lymphoid-committed hematopoietic progenitor cells.
7
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